Tr i p ath Technol ogy, I n c. - Techni cal I n for m ati on

6

TC2000 – KLI/1.1/12-03

turn-off of one transistor and the turn-on of the other in order to minimize shoot-through currents. For

applications using the TP2050 please tie BBM0 and BBM1 to 5V for optimal operation.

Input Sta g e De s i gn

The TC2000 input stage is configured as an inverting amplifier, allowing the system designer flexibility

in setting the input stage gain and frequency response. Figure 1 shows a typical application where

the input stage is a constant gain inverting amplifier. The input stage gain should be set so that the

maximum input signal level will drive the input stage output to 4Vpp.

TC2000

INPUT2

OAOUT2

V5

OAOUT1

+

-

CI

+

-

INV1

INPUT1

BIASCAP

AGND

RF

RI

CI

RF

AGND

INV2

V5

RI

Figure 1: Input Stage

The gain of the input stage, above the low frequency high pass filter point, is that of a simple inverting

amplifier: It should be noted that the input amplifiers are biased at approximately 2.5VDC. Thus, the

I

F

STAGE

INPUT

V

R

R

A

−

=

Input Ca pa c i tor Se le c t ion

I

P

I

R

f

2

1

C

π

=

where:

I

P

Modulator Feedback Design

The modulator converts the signal from the input stage to the high-voltage output signal. The

optimum gain of the modulator is determined from the maximum allowable feedback level for the

modulator and maximum supply voltage for the power stage. Depending on the maximum supply

voltage, the feedback ratio will need to be adjusted to maximize performance. The values of RFBB

and RFBC (see explanation below) define the gain of the modulator. Once these values are chosen,

based on the maximum supply voltage, the gain of the modulator will be fixed even as the supply

voltage fluctuates due to current draw.